Search results for "POLYPROPYLENE"
showing 10 items of 177 documents
Experimental and numerical investigation on a new FSW based metal to composite joining technique
2018
Abstract In the last decades, different techniques were proposed to join aluminum sheets with composites materials. Each of them has advantages and weak points over the others and new techniques and patents are continuously developed to overcome these difficulties. In this paper an experimental and numerical investigation on a new Friction Stir Welding based approach to mechanically join AA6082-T6 to self-reinforced polypropylene is presented. The aluminum sheet is pre-holed along both the sides of the weld line and a pinless tool generates the heat and pressure needed to prompt back-extrusion of the composite. New experimental fixtures and hole designs were investigated in order to enhance…
A macroscale FEM-based approach for selective laser sintering of thermoplastics
2017
A numerical approach to model the selective laser sintering (SLS) of polypropylene is proposed. A 3D thermal model was developed and thus enables the prediction of the temperature fields and the extension of the sintered area in the powder bed taking into account the phase change during multiple laser passes. Powderâliquid, liquidâsolid and solidâliquid phase changes were modelled during the SLS and the subsequent cooling processes. Then, a 3D thermomechanically coupled model was set up based on the temperature results of the thermal model in order to predict the distortion of the produced parts after cooling down. Different pre-heating temperatures were considered, highlighting their…
An Additive Model to Predict the Rheological and Mechanical Properties of Polypropylene Blends Made by Virgin and Reprocessed Components
2021
In this work, an additive model for the prediction of the rheological and mechanical properties of monopolymer blends made by virgin and reprocessed components is proposed. A polypropylene sample has been reprocessed more times in an extruder and monopolymer blends have been prepared by simulating an industrial process. The scraps are exposed to regrinding and are melt reprocessed before mixing with the virgin polymer. The reprocessed polymer is, then, subjected to some thermomechanical degradation. Rheological and mechanical experimental data have been compared with the theoretical predictions. The results obtained showed that the values of this simple additive model are a very good fit fo…
Morphogenetically-Active Barrier Membrane for Guided Bone Regeneration, Based on Amorphous Polyphosphate
2017
We describe a novel regeneratively-active barrier membrane which consists of a durable electrospun poly(ε-caprolactone) (PCL) net covered with a morphogenetically-active biohybrid material composed of collagen and inorganic polyphosphate (polyP). The patch-like fibrous collagen structures are decorated with small amorphous polyP nanoparticles (50 nm) formed by precipitation of this energy-rich and enzyme-degradable (alkaline phosphatase) polymer in the presence of calcium ions. The fabricated PCL-polyP/collagen hybrid mats are characterized by advantageous biomechanical properties, such as enhanced flexibility and stretchability with almost unaltered tensile strength of the PCL net. The pol…
Collagen-inducing biologization of prosthetic material for hernia repair: Polypropylene meshes coated with polyP/collagen
2017
Prostethic mesh material such as nonabsorbable polypropylene used in open and laparoscopic hernia repair are characterized by controllable mechanical properties but may elicit undesirable physiological reactions due to the nonphysiological inert polymer material. We succeeded in developing a biocompatible coating for these meshes, based on a physiological inorganic polymer, polyphosphate (polyP) that is morphogenetically active and used as a metabolic energy source, and a collagen matrix. The polyP/collagen hydrogel material was prepared by a freeze-extraction method, with amorphous Ca-polyP microparticles. Electron microscopy (SEM and REM) studies revealed that the polyP/collagen coats are…
Influence d'humidité de l'air sur le séchage d'une goutte déposée sur une surface solide et sur la destruction microbienne.
2017
International audience; This study was carried out in order to develop experimental methodology using a camera to monitor the evolution of the surface of a liquid droplet deposited on a solid surface composed of polypropylene. The droplet was exposed to various ambient relative humidity conditions (11.3%, 43.2%, 68.9% and 75.5%). Two types of liquid were investigated: distilled water and water containing nutritive substances (salmon “juice”). At 11.3% relative humidity, it takes 40% longer to evaporate a water droplet (initial weight 0.36 g, volume 360 μL, radius 6.5 × 10−3 m) than a salmon “juice” droplet (3.66 h for distilled water, 2.83 h for salmon “juice”). In the case of the distilled…
On the variations of acoustic absorption peak with particle velocity in micro-perforated panels at high level of excitation.
2010
The acoustic behavior of micro-perforated panels (MPP) is studied theoretically and experimentally at high level of pressure excitation. A model based on Forcheimer's regime of flow velocity in the perforations is proposed. This model is valid at relatively high Reynolds numbers and low Mach numbers. The experimental method consists in measuring the acoustical pressure at three different positions in an impedance tube, the two measurement positions usually considered in an impedance tube and one measurement in the vicinity of the rear surface of the MPP. The impedance tube is equipped with a pressure driver instead of the usual loudspeaker and capable of delivering a high sound pressure lev…
Impact of Heavy Polypropylene Mesh and Composite Light Polypropylene and Polyglactin 910 on the Inflammatory Response
2010
The aim of the study was to analyze the acute inflammatory response after implantation of a heavyweight mesh of polypropylene (PP) compared with a composite mesh of light PP and polyglactin 910 (PG) in patients undergoing inguinal hernioplasty. A total of 30 male patients with inguinal hernia were included in the study and divided into 2 groups (PP and PP-PG) according to the mesh used. Changes of leukocytes, cytokines, growth factors, and acute phase proteins were evaluated in the sera. Leukocytes and acute phase proteins were significantly increased postoperatively in both groups, and the values were slightly higher in the PP group. Cytokine levels were significantly increased postoperat…
Modified fixation free plug technique using a new 3D multilamellar implant for inguinal hernia repair: a retrospective study of a single operator cas…
2013
Aim: Implant fixation, mesh shrinkage and poor quality of tissue ingrowth are unresolved issues in modern hernia repair. Many complications reported in the literature such as bleeding, nerve entrapment, hematoma, pain, discomfort, and testicular complications, are considered to be a direct results of implant fixation. This article describes the outcomes of a procedure carried out using a handcrafted implant that addresses the issues consequent to point fixation. Methods: This was a retrospective study on the short, medium and long-term results of placing a-modified, fixation free three-dimensional polypropylene implant in 61 patients who underwent inguinal hernia repair using a novel delive…
Impact of Different Texture of Polypropylene Mesh on the Inflammatory Response
2008
Over the past decade, hernia surgery has undergone a considerable transformation with the use of prosthetic materials. The most used polypropylene meshes induce a rapid acute inflammatory response followed by chronic foreign body reaction. Many factors influence this response such as density, size, physical characteristics, different texture and porosity of each biomaterial. The aim of this study is to assess whether the implant of monofilament or multifilament meshes, in the inguinal hernioplasty, determine a different inflammatory response. Thirty-two male patients were included in the study and were randomly divided into two groups. In the first group (MO) inguinal hernioplasty was perf…